And a code signing would be absolutely useless, seeing as how that signature would simply be duplicated. The thing about code signing is that it's only useful as long as the signature isn't reversed, as soon as it is the signature might as well not even be there. On a software platform such as a typical PC or even a cel phone, this wouldn't be a big deal as the signature certificates could simply be updated in the background, but on a tiny embedded system it would be worse than useless even if they did bother to implement it. I doubt many would continuously update their keyboard firmware for new signatures, and it would be too risky to have firmware updates applied automatically without prompting in case the device was bricked due to a crash or loss of power.